Control apparatus for vehicle

Abstract

A control apparatus for a vehicle that includes an engine, an electric motor, a clutch for separating connection between the engine and the electric motor, and a fluid-type transmission device including a lockup clutch and transmitting drive powers of the engine and the electric motor to drive wheels. The control apparatus includes (a) a portion configured, during motor running of the vehicle with the clutch being released, to calculate a predicted value of a rotational speed of the electric motor, depending on an operation state of the lockup clutch; (b) a portion configured to calculate a predicted value of an outputtable maximum torque of the electric motor, by using the predicted value of the rotational speed of the electric motor; (c) a portion configured to determine whether start of the engine is requested or not, by using the predicted value of the outputtable maximum torque of the electric motor.

What is claimed is: 
     
       1. A control apparatus for a vehicle that includes (i) an engine, (ii) drive wheels, (iii) an electric motor provided in a power transmission path between the engine and the drive wheels and connected to the engine and the drive wheels in a power transmittable manner, (iv) a clutch provided in the power transmission path, and configured to separate connection between the engine and the electric motor when the clutch is released, and (v) a fluid-type transmission device including a lockup clutch and constituting a part of the power transmission path so as to transmit a drive power of the engine and/or a drive power of the electric motor to the drive wheels,
 the control apparatus comprising: 
 an electric-motor rotational-speed prediction portion that is configured, during motor running of the vehicle by the drive power of the electric motor with the clutch being released, to calculate a predicted value of a rotational speed of the electric motor, by anticipating change of the rotational speed of the electric motor, depending on an operation state of the lockup clutch; 
 an electric-motor torque prediction portion that is configured to calculate a predicted value of an outputtable maximum torque of the electric motor, by using the predicted value of the rotational speed of the electric motor; 
 an engine-start-request determination portion that is configured to determine whether start of the engine is requested or not, by using the predicted value of the outputtable maximum torque of the electric motor; and 
 an engine-start control portion that is configured, when it is determined that the start of the engine is requested, to start the engine by causing the electric motor to output a required starting torque required to start the engine while causing the clutch to be engaged, 
 wherein the electric-motor rotational-speed prediction portion is configured, in a case in which the lockup clutch is in a released state, to calculate the predicted value of the rotational speed of the electric motor, based on an output rotational speed of the fluid-type transmission device, a requested drive amount of the vehicle requested by a driver of the vehicle and an operation characteristic of the fluid-type transmission device. 
 
     
     
       2. The control apparatus according to  claim 1 ,
 wherein the electric-motor rotational-speed prediction portion is configured, in a case in which the lockup clutch is in an engaged state, to calculate, as the predicted value of the rotational speed of the electric motor, a sum of an output rotational speed of the fluid-type transmission device and a slip rotational speed of the lockup clutch in process of the start of the engine. 
 
     
     
       3. The control apparatus according to  claim 1 ,
 wherein the vehicle further includes an electrical storage device configured to supply and receive an electric power to and from the electric motor, and 
 wherein the electric-motor torque prediction portion is configured to calculate the predicted value of the outputtable maximum torque of the electric motor, based on a limitation of output from the electrical storage device and the predicted value of the rotational speed of the electric motor. 
 
     
     
       4. The control apparatus according to  claim 1 ,
 wherein the engine-start-request determination portion is configured to determine whether the start of the engine is requested or not, depending on whether a requested drive amount of the vehicle requested by a driver of the vehicle has exceeded an engine-start determination value that is obtained by subtracting the required starting torque from the predicted value of the outputtable maximum torque of the electric motor. 
 
     
     
       5. The control apparatus according to  claim 4 ,
 wherein the engine-start control portion is configured, when it is determined that the start of the engine is requested, to set an upper limit of the requested drive amount, to the engine-start determination value at a point of time at which it is determined that the start of the engine is requested, and to keep the upper limit of the requested drive amount in a period until the start of the engine is completed. 
 
     
     
       6. The control apparatus according to  claim 1 ,
 wherein the engine-start-request determination portion is configured to determine whether the start of the engine is requested or not, depending on whether a requested drive amount of the vehicle requested by a driver of the vehicle has exceeded an engine-start determination value that is obtained by subtracting a sum of the required starting torque and a margin amount of the outputtable maximum torque from the predicted value of the outputtable maximum torque of the electric motor, and 
 wherein the margin amount of the outputtable maximum torque is dependent on accuracy of calculation of the predicted value of the rotational speed of the electric motor. 
 
     
     
       7. The control apparatus according to  claim 6 ,
 wherein the engine-start control portion is configured, when it is determined that the start of the engine is requested, to set an upper limit of the requested drive amount, to a sum of the margin amount of the outputtable maximum torque and the engine-start determination value at a point of time at which it is determined that the start of the engine is requested, and to keep the upper limit of the requested drive amount in a period until the start of the engine is completed. 
 
     
     
       8. A control apparatus for a vehicle that includes (i) an engine, (ii) drive wheels, (iii) an electric motor provided in a power transmission path between the engine and the drive wheels and connected to the engine and the drive wheels in a power transmittable manner, (iv) a clutch provided in the power transmission path, and configured to separate connection between the engine and the electric motor when the clutch is released, and (v) a fluid-type transmission device including a lockup clutch and constituting a part of the power transmission path so as to transmit a drive power of the engine and/or a drive power of the electric motor to the drive wheels,
 the control apparatus comprising: 
 an electric-motor rotational-speed prediction portion that is configured, during motor running of the vehicle by the drive power of the electric motor with the clutch being released, to calculate a predicted value of a rotational speed of the electric motor, by anticipating change of the rotational speed of the electric motor, depending on an operation state of the lockup clutch; 
 an electric-motor torque prediction portion that is configured to calculate a predicted value of an outputtable maximum torque of the electric motor, by using the predicted value of the rotational speed of the electric motor; 
 an engine-start-request determination portion that is configured to determine whether start of the engine is requested or not, by using the predicted value of the outputtable maximum torque of the electric motor; and 
 an engine-start control portion that is configured, when it is determined that the start of the engine is requested, to start the engine by causing the electric motor to output a required starting torque required to start the engine while causing the clutch to be engaged, 
 wherein the vehicle further includes an electrical storage device configured to supply and receive an electric power to and from the electric motor, and 
 wherein the electric-motor torque prediction portion is configured to calculate the predicted value of the outputtable maximum torque of the electric motor, based on a limitation of output from the electrical storage device and the predicted value of the rotational speed of the electric motor. 
 
     
     
       9. The control apparatus according to  claim 8 ,
 wherein the electric-motor rotational-speed prediction portion is configured, in a case in which the lockup clutch is in an engaged state, to calculate, as the predicted value of the rotational speed of the electric motor, a sum of an output rotational speed of the fluid-type transmission device and a slip rotational speed of the lockup clutch in process of the start of the engine. 
 
     
     
       10. The control apparatus according to  claim 8 ,
 wherein the engine-start-request determination portion is configured to determine whether the start of the engine is requested or not, depending on whether a requested drive amount of the vehicle requested by a driver of the vehicle has exceeded an engine-start determination value that is obtained by subtracting the required starting torque from the predicted value of the outputtable maximum torque of the electric motor. 
 
     
     
       11. The control apparatus according to  claim 10 ,
 wherein the engine-start control portion is configured, when it is determined that the start of the engine is requested, to set an upper limit of the requested drive amount, to the engine-start determination value at a point of time at which it is determined that the start of the engine is requested, and to keep the upper limit of the requested drive amount in a period until the start of the engine is completed. 
 
     
     
       12. The control apparatus according to  claim 8 ,
 wherein the engine-start-request determination portion is configured to determine whether the start of the engine is requested or not, depending on whether a requested drive amount of the vehicle requested by a driver of the vehicle has exceeded an engine-start determination value that is obtained by subtracting a sum of the required starting torque and a margin amount of the outputtable maximum torque from the predicted value of the outputtable maximum torque of the electric motor, and 
 wherein the margin amount of the outputtable maximum torque is dependent on accuracy of calculation of the predicted value of the rotational speed of the electric motor. 
 
     
     
       13. The control apparatus according to  claim 12 ,
 wherein the engine-start control portion is configured, when it is determined that the start of the engine is requested, to set an upper limit of the requested drive amount, to a sum of the margin amount of the outputtable maximum torque and the engine-start determination value at a point of time at which it is determined that the start of the engine is requested, and to keep the upper limit of the requested drive amount in a period until the start of the engine is completed.